Tolstoy/Sinclair

“I know that most men, including those at ease with problems of the greatest complexity, can seldom accept even the simplest and most obvious truth if it be such as would oblige them to admit the falsity of conclusions which they have delighted in explaining to colleagues, which they have proudly taught to others, and which they have woven, thread by thread, into the fabric of their lives.”
– Leo Tolstoy.

Or simply put.

“It is difficult to get a man to understand something when his salary depends upon his not understanding it.”
– Upton Sinclair.